CVE-2025-12890 is a vulnerability identified in the Zephyr real-time operating system (RTOS), which is widely used in embedded and IoT devices. The flaw arises from improper validation and handling of malformed Bluetooth Low Energy (BLE) Connection Requests. Specifically, when a connection request is crafted with an interval value set to 1, which is outside the allowed range, and a channel map (chM) set to 0x7CFFFFFFFF, the system fails to handle this exceptional condition correctly. This triggers a crash in the peripheral device running Zephyr, causing it to become unconnectable via Bluetooth. The vulnerability affects all versions of Zephyr, indicating a systemic issue in the BLE connection request handling logic. The attack vector is remote and requires no authentication or user interaction, making it relatively easy to exploit by an attacker within Bluetooth range. The CVSS v3.1 score of 6.5 reflects a medium severity level, primarily due to the impact on availability (denial of service) without affecting confidentiality or integrity. No known exploits have been reported in the wild yet, but the vulnerability poses a significant risk to devices relying on Zephyr for Bluetooth connectivity. The lack of patch links suggests that a fix may not yet be publicly available, emphasizing the need for vigilance and interim mitigations.

The primary impact of CVE-2025-12890 is a denial of service (DoS) condition on Bluetooth peripherals running Zephyr RTOS. A successful exploit causes the device to crash and become unconnectable, disrupting normal operations. For European organizations deploying Zephyr-based IoT devices in critical infrastructure, industrial automation, healthcare, or consumer electronics, this can lead to operational downtime, loss of device availability, and potential safety risks if devices are part of safety-critical systems. While confidentiality and integrity are not directly compromised, the loss of availability can indirectly affect business continuity and service reliability. The remote and unauthenticated nature of the exploit increases the threat level, especially in environments with many Bluetooth-enabled devices. The impact is more pronounced in sectors with high reliance on embedded Bluetooth devices, such as manufacturing plants, smart cities, and healthcare facilities across Europe.

1. Monitor Zephyr project communications and security advisories closely for official patches addressing CVE-2025-12890 and apply them promptly once available. 2. Implement Bluetooth network segmentation and access controls to limit exposure of vulnerable devices to untrusted or external Bluetooth sources. 3. Use Bluetooth device whitelisting to restrict connections only to known and trusted devices, reducing the attack surface. 4. Employ runtime monitoring and anomaly detection on Bluetooth traffic to identify and block malformed connection requests with suspicious parameters such as illegal intervals or channel maps. 5. For critical deployments, consider disabling Bluetooth connectivity temporarily or using alternative communication protocols until patches are applied. 6. Conduct thorough testing of Zephyr-based devices in controlled environments to validate resilience against malformed BLE packets. 7. Collaborate with device manufacturers to ensure firmware updates incorporate fixes and security hardening against such malformed packet attacks.